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Topology of three-dimensional Dirac semimetals and quantum spin Hall systems without gapless edge modes

Physical Review Research 2023年第1期5卷 L012019-L012019页

作者： Alexander C. Tyner Shouvik Sur Danilo Puggioni James M. Rondinelli Pallab Goswami Graduate Program in Applied Physics Northwestern University Evanston Illinois 60208USA Department of Physics and Astronomy Northwestern University Evanston Illinois 60208 USA Department of Materials Science and Engineering Northwestern University Illinois 60208 USA Northwestern Argonne Institute for Science and Engineering Evanston Illinois 60208 USA

The quantum spin Hall states are usually expected to possess gapless, helical edge modes. We show that the generic, n-fold-symmetric, momentum planes of three-dimensional, stable Dirac semimetals, which are orthogonal to the direction of nodal separation are examples of generalized quantum spin Hall systems, that possess quantized, spin or relative Chern numbers as bulk topological invariants, and gapped edge modes. We demonstrate these planes and the celebrated Bernevig-Zhang-Hughes model support identical quantized, non-Abelian Berry flux of magnitude 2π. Hence, they display identical quantized, topological response such as spin-charge separation and pumping of one Kramers-pair or SU(2) doublet, when probed with a magnetic flux tube. The Dirac points are identified as unit-strength, monopoles of SO(5) Berry connection, describing topological phase transitions between generalized quantum spin Hall and trivial insulators. Our work identifies precise bulk invariant and quantized response of Dirac semimetals, which are not diagnosed by nested Wilson loops and filling anomaly of corner-localized-states, and shows that many two-dimensional higher-order topological insulators can be understood as generalized quantum spin Hall systems.

关键词： Fractionalization Geometric & topological phases Spintronics Topological insulators Topological phase transition Topological phases of matter

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Enhanced Heterogeneous Photocatalytic Degradation of Florasulam in Aqueous Media Using Green Synthesized Tio2 Nanoparticle Under Uv Light Irradiation

SSRN

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SSRN 2023年

作者： Purkait, Pijushkanti Majumder, Sambrita Roy, Sankhajit Maitra, Saikat Das, Gopes Chandra Chaudhuri, Mahua Ghosh School of Materials Science & Nanotechnology Jadavpur University West Bengal Kolkata700032 India Department of Agricultural chemicals Bidhan Chandra Krishi Viswavidyalaya Mohanpur West Bengal Nadia India Department of Ceramic Technology Government College of Engineering & Ceramic Technology West Bengal Kolkata700010 India Metallurgical & Material Engineering Department Jadavpur University West Bengal Kolkata700032 India

In the present study investigated the potential of green synthesized titanium dioxide nanoparticles (TiO2 NPs) for the photocatalytic degradation of florasulam, a triazolopyrimidine sulfonanilide herbicide under UV light irradiation. The green synthesis of TiO2NPs was confirmed by the powder X-ray diffraction (XRD) analysis and the average crystalline size was calculated by Scherrer’s formula (67.47 nm), Williamson-Hall (W-H) equation (79.66 nm) and as well as the Dynamic Light Scattering (DLS) analysis showed the stability and average particle size approximately 86.8 nm. The Fourier Transform Infrared Spectroscopy (FTIR) analysis confirmed the presence of various functional groups in the synthesized NPs. The UV absorption wavelength is observed at 351 nm, and the calculated direct and indirect bandgap value for synthesized TiO2 NPs is 3.62 eV and 3.22 eV respectively. Surface morphology and crystalline shape of the synthesized TiO2NPs was determined by using Scanning Electron Microscopy (SEM).The photodegradation experiment was carried out using a batch reactor process. The calculated half-lives of photodegradation of florasulam in the aqueous medium were found to be in the range of 27.57 - 97.11 h. The influence of different experimental parameters like effect of pH, the initial concentration of florasulam and photocatalyst TiO2 NPs dosage were investigated. The experimental kinetic data followed the pseudo-first-order model. The reaction rate constant (kobs) was decreased from 0.02514 to 0.02141 h-1 with increasing initial florasulam concentration from 100 to 250 mg/L, respectively. Langmuir–Hinshelwood (L–H) kinetic model was proposed for the rate equation of the florasulam degradation in presence of TiO2 NPs under UV irradiation. © 2023, The Authors. All rights reserved.

关键词： Titanium dioxide

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Long-range order of polygonal grain boundaries

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Physical Review B 2025年第4期111卷 045103-045103页

作者： N. Sarkar P. R. Bandaru R. C. Dynes Department of Mechanical Engineering University of California San Diego La Jolla California 92093-0411 USA Program in Materials Science University of California San Diego La Jolla California 92093-0411 USA Department of Physics University of California San Diego La Jolla California 92093-0411 USA

Atomic-scale spatial resolution was achieved in the mapping and spectroscopy of polygonal grain boundaries (GBs) on atomically flat highly oriented pyrolytic graphite using scanning tunneling microscopy (STM). These GBs are long-range ordered one-dimensional periodic structures comprising pentagon-heptagon pairs. A comprehensive study combining local electronic, valleytronic, mechanical, and topological properties is conducted on this GB which reveals the interplay between these properties. On the atoms and bonds of individual GB polygons, spatially localized conductance states were probed, in addition to edge states. The spatial extent of these states was observed on GB by bias-dependent imaging. The electron scattering angle at the GB edges was also modulated with a sample bias which exhibited valley flipping and unique quantum interference effects such as backscattering and intervalley scattering. In situ strain-induced mechanical and electronic modifications were observed through surface deformation caused by the STM tip, revealing flattened electronic energy band dispersion and shifts in carrier doping.

关键词： Grain boundaries

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Development of Flexible Sendust Composite Sheets with Enhanced Magnetic Permeability for Microwave Absorbers and Antennas

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IEEE Transactions on Magnetics 2025年

作者： Whalen, Matthew P. Plouff, David T. Shevchenko, Nicholas B. Mirotznik, Mark Xiao, John Q. University of Delaware Quantum Science and Engineering Program NewarkDE19716 United States University of Delaware Department of Physics and Astronomy NewarkDE19716 United States University of Delaware Center for Composite Materials NewarkDE19716 United States University of Delaware Department of Electrical and Computer Engineering NewarkDE19716 United States

The demand for high-frequency soft magnetic composites with elevated permeability and flexibility is growing for applications in microwave absorbers and magnetodielectric antennas. However, balancing high permeability with mechanical flexibility remains challenging. This study presents flexible Sendust (FeSiAl) composite sheets, fabricated with a hot-pressing technique that aligns flakes within an acrylic rubber and epoxy resin matrix. The alignment significantly enhances relative permeability at high frequencies, achieving single-layer film properties of μr' = 14.8 and μr"= 20.4 at 1 GHz, alongside high saturation magnetization (118 eμg) and high hesitivity (44.7 kΩ m-1), outperforming commonly used materials such as NiZn ferrite. Our method supports customizable thickness without sacrificing permeability, establishing a versatile platform for advanced conformal microwave absorber and antenna applications. © 2025 IEEE.

关键词： Saturation magnetization

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Facile Synthesis, Structure and Battery-Type Behavior of Graphene Oxides

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SSRN 2023年

作者： Silva, Jullyani M.D. Fenandes, Filipe P.M. Silva, Mariana de O. Maraschin, Thuany G. Ferreira, Luciena S. Macedo, Daniel A. da Silva, Lucineide B. Fim, Fabiana de C. Materials Science and Engineering Postgraduate Program UFPB João Pessoa58051-900 Brazil Department of Materials Engineering UFPB Paraíba João Pessoa58051-900 Brazil RS Porto Alegre90619-900 Brazil

Graphene oxide (GO) is one of the main precursors for the production of graphene and other graphene-based materials. In this work, we report a simple, safe and fast synthesis method for obtaining graphene oxide as a functional material for battery-type electrodes. The method provides to obtain an aqueous solution of graphene oxide suitable for drying by freeze-drying (sample GO1). Washing and freeze-drying processes are performed to assess their effects on the exfoliation and removal of functional groups from the graphene sheets (sample GO2). GO1 sample consists of a stack of 10 oxidized graphene layers without any additional exfoliation process, while the GO2 sample has 8 stacked layers, after two washing and freeze-drying processes. FTIR results indicate that bulkier groups such as carboxylic acid are most likely to be found on the edges and surfaces of the graphene sheets of both samples. The presence of point defects such as vacancies was also observed in both samples, with the GO2 sample having a higher content of vacancies. The electrochemical performance of graphene oxide-based electrodes, classified as battery-type, indicate an improved specific capacity of 10.15 C g-1 for GO1 against 4.55 C g-1 for GO2 at a specific current of 0.5 A g-1. This superior battery-type behavior of the GO1 electrode, also confirmed by electrochemical impedance spectroscopy, is most likely due to a higher degree of oxygenated groups on its surface, as shown by EDS and FTIR studies. © 2023, The Authors. All rights reserved.

关键词： Washing

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Propolis nanoemulsion extract from celebes stingless bee (Tetragonula biroi) phytochemistry and antibacterial analysis to periodontopathogen bacteria

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Journal of Oral Biology and Craniofacial Research 2025年第3期15卷 576-584页

作者： Amalia, Nadya Rafika Budhy, Theresia Indah Ridwan, Rini Devijanti Rianti, Devi Bramantoro, Taufan Luthfi, Muhammad Ramadhani, Nastiti Faradilla Pramusita, Adya Putranti, Nurul Aisyah Rizki Nugraha, Albertus Putera Situmorang, Putri Cahaya Shariff, Khairul Anuar Nugraha, Alexander Patera Dental Health Science Study Program Faculty of Dental Medicine Universitas Airlangga Surabaya Indonesia Department of Oral and Maxillofacial Pathology Faculty of Dental Medicine Universitas Airlangga Surabaya Indonesia Department of Oral Biology Faculty of Dental Medicine Universitas Airlangga Surabaya Indonesia Department of Dental Material Faculty of Dental Medicine Universitas Airlangga Surabaya Indonesia Department of Dental Public Health Faculty of Dental Medicine Universitas Airlangga Surabaya Indonesia Department of Dentomaxillofacial Radiology Faculty of Dental Medicine Universitas Airlangga Surabaya Indonesia Department of Orthodontic Faculty of Dental Medicine Universitas Airlangga Surabaya Indonesia Faculty of Medicine Universitas Airlangga Surabaya Indonesia Biology Study Program Faculty of Mathematics and Natural Sciences Universitas Sumatera Utara Medan Indonesia School of Materials and Mineral Resources Engineering Engineering Campus Universiti Sains Malaysia Penang Nibong Tebal 14300 Malaysia

Background: Propolis from Sulawesi's stingless bees (Tetragonula biroi) contains antioxidants, more flavonoids than propolis from Apis bees, and the antibacterial ability. Objective: to examine the antibacterial properties of Propolis Nanoemulsion Extract (PNE), which is extracted from the Celebes Stingless Bee (T. biroi), in relation to the periodontopathogen bacteria such as Fusobacterium nucleatum (Fn), Porphyromonas gingivalis (Pg), Aggregatibacter actinomycetemcomitans (Aa), and Provotella intermedia (Pi). This investigation also examines PNE's phytochemistry, particle size analysis (PSA), and zeta potential. Methods: The maceration process with 96 % ethanol was used to create PNE from Celebes stingless bee (T. biroi), which was then subjected to zeta potential measurement and PSA. Phytochemical analysis was used to identify phytochemical constituents in the PNE (T. biroi). Diffusion zone, minimum bactericidal concentration (MBC), and minimum inhibitory concentration (MIC) were used to assess antibacterial efficacy against Aa, Pg, Pi, and Fn. Furthermore, the statistical analysis was used to extract the data. Results: Phenols, alkaloids, and flavonoids were identified;however, triterpenoids and saponins were not. Between 151.28 and 182.2 diameter nanometers (***) was the range of the PNE's diameter. At 1.56 % propolis (T. biroi) concentration, the MIC, MBC, and diffusion zone analysis performed better than at 0.76 %, with a significant difference (p:0.01;p < 0.05) to Aa, Pg, Pi, and Fn. Conclusions: The highest antibacterial activity against Aa, Pg, Pi, and Fn as periodontopathogen bacteria is demonstrated by alkaloids, flavonoids, and phenols in PNE from Celebes (T. biroi) at a concentration of 1.56 %. © 2025 The Authors

关键词： Antibacterial Communicable disease Infectious disease Medicine Periodontal disease

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Efficient Automatic External Defibrillator Using the Slope of Hilbert Transformed ECG Signals

Efficient Automatic External Defibrillator Using the Slope o...

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Electronics, Communications, and Computations (JAC-ECC), International Japan-Africa Conference on

作者： Samir A. Elsagheer Mohammed S. Sayed Mohsen A. Hassan Computer Science and Information Technology Egypt-Japan University of Science and Technology Alexandria Egypt Facurlty of Engineering Aswan Universty Aswan Egypt Department of Electronics and Communications Engineering Egypt-Japan University of Science and Technology Alexandria Egypt Department of Electronics and Communications Engineering Zagazig University Zagazig Egypt Materials science and engineering program IDE Egypt-Japan University of Science and Technology Alexandria Egypt

Sudden cardiac arrest (SCA) is a life-threatening condition that demands immediate intervention. The key to survival often lies in the timely and precise analysis of electrocardiogram (ECG) signals to determine the necessity of a shock from an Automatic External Defibrillator (AED). In this paper, we address the critical need for improved accuracy in AED decision-making by presenting a novel approach that leverages the Hilbert Transform to calculate the slope of ECG signals by harnessing the analytical power of Hilbert Transformed ECG signals. By scrutinizing the heart's electrical activity through this method, we aim to enhance the AED's ability to differentiate between cases of ventricular fibrillation and other non-shockable rhythms, ultimately leading to more efficient and effective treatment. Our research explores two distinct approaches for signal analysis and correlates their findings to achieve higher precision in defibrillation decisions. To validate the effectiveness of our approach, we employ a diverse and publicly available dataset containing various heart conditions, allowing us to demonstrate the robustness of our method across a wide spectrum of cases. This study represents a significant advancement in the field of automatic external defibrillation, with the potential to save countless lives through more accurate and timely interventions.

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Efficient synthesis method of CsPbBr3/Al2O3 composite powders for scalable production: Augmented green emission and thermal stability

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Journal of Industrial and engineering Chemistry 2025年

作者： Kim, Seok-Hun Shin, Weon Ho Oh, Jong-Min Kim, Sang-Wook Kim, Sunghoon Center for Brain Busan 21 Plus Program Dong-Eui University Busan47340 Korea Republic of Department of Electronic Materials Engineering Kwangwoon University Seoul01897 Korea Republic of Department of Molecular Science and Technology Ajou University Suwon16499 Korea Republic of

Metal halide perovskites (MHPs) have gained significant attention for their exceptional optoelectronic properties, particularly in displays. However, their practical utility is severely limited by their intrinsic instability, including poor thermal stability, photostability, and susceptibility to moisture-induced degradation. This study introduces scalable synthesis of CsPbBr3/Al2O3 green-emitting phosphors, using submicron Al2O3 as a support, comparing mechanochemical reaction (MRM) and dissolution-evaporation (DEM) methods. DEM is the optimal route, enabling the formation of monoclinic CsPbBr3/Al2O3 with high photoluminescence quantum yield (PLQY) and enhanced stability. The influence of the CsPbBr3 to Al2O3 mass ratio on PLQY was quantitatively analyzed using the Halder-Wagner method, which indirectly calculated crystallite size and its correlation with PLQY. The composite demonstrated exceptional thermal stability, maintaining over 90 % of its initial PL intensity after 200 °C exposure for 15 days and showed excellent photostability, maintaining nearly its initial luminous efficiency under the currents of 20 mA and 70 mA for 10000-seconds. When integrated as a green phosphor in a white LED package with K2SiF6:Mn+4 as a red phosphor, it achieved a luminous efficiency of 25 lm W−1 and a color gamut of 112.4 % NTSC. These results highlight the potential of CsPbBr3/Al2O3 composites for cost-effective, stable, and high-performance optoelectronic applications. © 2025 The Korean Society of Industrial and engineering Chemistry

关键词： Perovskite

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Low voltage graphene interface engineered organic ferroelectric tunnel junction devices

arXiv

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arXiv 2025年

作者： Natani, S. Khajanji, P. Cheng, L. Eshraghi, K. Zhang, Z. Shipley, W. Tao, A. Bandaru, P.R. Department of Mechanical Engineering University of California San Diego La Jolla CA United States Program in Materials Science University of California San Diego La Jolla CA United States Applied Materials Santa ClaraCA United States

It has been indicated 1 that the path forward for the widespread usage of ferroelectric (FE) materials may be considerably facilitated through the reduction of programming voltages to on-chip logic compatible values o... 详细信息

关键词： Ferroelectric devices

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Multi-Scale Characterization of Supersaturated and Intermetallic Nanoscale Phases in an Al-Mg Alloy Produced by High-Pressure Torsion

SSRN

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SSRN 2024年

作者： Wu, Yun-Hsuan Bhatta, Laxman Lee, Isshu Figueiredo, Roberto B. Kawasaki, Megumi Santala, Melissa K. Materials Science Program Oregon State University CorvallisOR97331 United States School of Mechanical Industrial and Manufacturing Engineering Oregon State University CorvallisOR97331 United States Department of Metallurgical and Materials Engineering Universidade Federal de Minas Gerais MG Belo Horizonte31270-901 Brazil

Nanostructured Al-Mg alloy was produced from disks of Mg sandwiched between Al through 100 turns of high-pressure torsion (HPT) at 6.0 GPa at room temperature, resulting in high microhardness of Hv 300–350 in regions experiencing a nominal shear strain greater than ~3500. While compositional mapping using scanning electron microscopy energy dispersive spectroscopy (EDS) showed a uniform distribution of Mg through the disk thickness at 1.5 and 3.0 mm from the disk center, transmission electron microscopy EDS showed a heterogeneous distribution of Mg remained on the nanoscale. Although HPT induces enough mixing to result in face-center-cubic Al with supersaturations of Mg of up to »20 at% near the disk surfaces, β-Al3Mg2, γ-Al12Mg17 and Al2Mg intermetallic phases were identified by electron diffraction throughout the disk thickness in regions experiencing high shear strain. This study captures detailed compositional heterogeneity throughout the sample thickness following intense mechanical alloying, nanoscale re-structuring, and phase transformations. © 2024, The Authors. All rights reserved.

关键词： Magnesium alloys

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